I am in the middle of doing this right now. Have been at it for 5 days. I am staying away from cardboard products because of the acid issue but am using Readi-board foam that I can purchase at our local dollar store. It costs me $1.00 for each 20X30 inch sheet and I cut mine so that I get 10 board out of each sheet. It is a reinforced styrofoam sheet and is working just fine for my needs. I tried the colorplast but it was more expensive and I didn't like the sharper edges. Probably would end up cutting myself on them eventually. Colorplast is a more rigid product than I am using and after the local elections you can pick up all the outdated candidate signs that are still around - I did get permission first just to be sure. I just didn't care for the sharper edges and it was harder to cut than the board that I am now using.